Former New Zealand under-19 international Coman initially joined Edinburgh in 2013, on a two-year deal, and was awarded the captaincy this season.
His 28 caps for the club include this season's 1872 Cup win over Glasgow Warriors and the bonus-point win over Bordeaux-Begles that saw Edinburgh through to the quarter-finals of the European Challenge Cup.
The 27-year-old back row most recently led the team to a bonus-point away victory over Treviso at the weekend, having scored a try in the win against the Italians when they visited BT Murrayfield earlier in the season.
Coman said: "We had a bit of a slow start to the season but the team's coming together really well and results are coming over time. The boys are working hard and the systems are coming together.
"The highpoint of this season for me has definitely been winning the 1872 Cup and progressing in Europe."
Having already led previous teams - from Nelson Bay under-16s to Hawke's Bay - Coman stresses he enjoys wearing the metaphorical armband.
"I enjoy the responsibility of being captain - although there are other duties off the field, it helps me focus on my game, and we've a great leadership group here at Edinburgh, so the support is always there.
"Looking ahead I just want to keep building on this season, making sure we're consistently a top six team and that we keep improving."
Edinburgh return to League competition, following this Six Nations window, on 28 March away to Scarlets, before embarking on the next leg of European action, the Cup quarter-final against London Irish at the Madejski Stadium on Sunday 5 April. The club's next home game is on Saturday 11 April against Munster.
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